The present invention, in some embodiments thereof, relates to devices and methods for efficiently converting energy associated with water waves into rotational energy, but not exclusively, to methods for effectively producing electrical energy from wave action.
There is a tremendous push in the world toward “renewable” energy sources. While solar and wind have been of the dominant varieties of alternative electricity sources, waves from the oceans could power a significant portion of the world electrical demand (see for example: http://peswiki.com/index.php/Directory:Ocean_Wave_Enemy). As with any form of energy supplied to the world public, wave-based electricity must be price competitive with other energy sources. Creating electricity is not the same as providing electricity in quantities and at prices that allow for its use in the electrical grid.
Wave-based electrical generators have been prepared and different versions have been used in sea trials, though none is commercially in use. While each system has unique features as well as performance specifications, most use the same basic physics of a wave driving either a linear or rotary element to eventually create electricity.
U.S. patent application Ser. No. 12/221,407 to Kim, et al describes electricity generation from the ocean wave by use of mechanical systems, submerged or on surface, collecting energy day and night regardless weather condition in a way similar to the way of collecting energy by use of solar panels or wind mills, without contacting the salty ocean water. The principal mechanism invented is as follows. Swinging of a heavy mass due to the ocean wave generates torque that sways gear wheel in clockwise or counterclockwise, thus transmitting the torque energy to two gear wheels that separate clockwise swing and counterclockwise swing via two sets of spring-piston clutching system and by use of gear chain, either converting clockwise swing to counterclockwise swing or vise versa such that the back and forth motion of the mass transforms into unidirectional rotation that rotates the rotor of electricity generator.
U.S. patent application Ser. No. 12/248,575 to Rasmussen teaches systems and methods are disclosed for harnessing wave energy. In one embodiment, a wave energy conversion device comprises a buoyant component connected to a generator such that wave energy is transferable from the buoyant component to the generator. A restricting mechanism connected with the buoyant component, is configured to selectively restrict the buoyant component from rising strictly along with passing waves. The restricting mechanism may be selectively released at an optimal time during a passing wave. In some embodiments, a system may include an array of wave energy conversion devices and a communications network. The communications network may allow for each of the buoyant components in the array to be released at an optimal time in sequential fashion.
U.S. patent application Ser. No. 12/867,431 to Sidenmark describes a wave energy converter including a buoy and a transmission unit. In the transmission unit there is a driveshaft, which is driven to rotate either when the buoy rises or sinks, yet always in the same direction. The driveshaft is mechanically coupled to one of the rotating parts of an electric generator and drives this to generate electric current. Further on there is an energy accumulation device, which is also coupled to the driveshaft to accumulate energy when the buoy rises or sinks and the driveshaft rotates and which is then used to drive the generator at the other of the rising and sinking motions. The coupling between the energy accumulation device and the driveshaft can go by the generator's second rotatable part, the air gap between the generator's parts and the generator's first part. The coupling over the air gap gives a torque, which drives the second part to rotate along and which also counteracts the rotation of the driveshaft. The generator's second part is driven by the energy accumulation device to rotate in the other direction, when the torque from the driveshaft does not exceed the counteracting torque.
U.S. Pat. No. 4,568,836 to Reenberg teaches an apparatus for converting wave energy to electrical energy in a sea environment comprises a flotation duck anchored to the sea bottom and a turbine assembly pivotally connected thereto comprising an air chamber partially filled with liquid and/or granular particles having a turbine mounted on the upper portion thereof. The turbine is either self-rectifying or with a flap valve controlled entrance to the air chamber. A generator is coupled to the turbine and driven thereby. In operation, the motion of the waves causes the liquid and/or granular particles to compress the air within the chamber which is then used to drive the turbine. The spent air is fed back into the air chamber from the turbine as wave motion continues. In alternate embodiments the turbine generator assembly is mounted to the upper portion of an air chamber open to the sea on the bottom in an apparatus which rotates about a fixed or stable central axis. Gearing arrangements to drive the generator either alone or in combination with a liquid or air turbine drive are also disclosed. Compression of the air within the chamber or liquid, as the case may be, drives the turbine. Multiple assemblies may be readily coupled together to generate electrical energy in commercially practical quantities.
U.S. patent application Ser. No. 12/698,779 to Bender describes a power generating device comprising a weight suspended from a buoy via a zip-line and at least two gears disposed on said zip-line which are coupled to drives shafts, which in turn are couple to electric generators. The device converts the mechanical power of oscillating ocean waves into electricity.
U.S. Pat. No. 7,012,340 to Yi teaches an ocean wave energy conversion apparatus including a float adapted to ride on the surface of the ocean in reciprocal vertical motion in response to ocean wave front action and a lever adapted to ride on the surface of the ocean. The lever has one end coupled to the float. A fulcrum pivotally supports the lever. A magnet is coupled to the other end of the lever. Parallel stator cores having electric coils wound thereon together with the magnet form a magnetic circuit. Springs are adjacent the magnet and interconnected to the lever and the magnet. A barrier is disposed between adjacent stator cores. The upward motion of the float caused by impact of waves will move the magnet downward by the lever and compresses the springs. Downward motion of the float will move the magnet upward by the lever and expand the springs. Repeated movement of the magnet will induce a voltage in the electric coils.
The prior art generally describes production of electrical energy through the movement of weights with concomitant generation of electrical energy.